Array-Add to Array-Form of Integer

The array-form of an integer num is an array representing its digits in left to right order.

For example, for num = 1321, the array form is [1,3,2,1].
Given num, the array-form of an integer, and an integer k, return the array-form of the integer num + k.

 

Example 1:

Input: num = [1,2,0,0], k = 34
Output: [1,2,3,4]
Explanation: 1200 + 34 = 1234
Example 2:

Input: num = [2,7,4], k = 181
Output: [4,5,5]
Explanation: 274 + 181 = 455
Example 3:

Input: num = [2,1,5], k = 806
Output: [1,0,2,1]
Explanation: 215 + 806 = 1021
 

Constraints:

1 <= num.length <= 104
0 <= num[i] <= 9
num does not contain any leading zeros except for the zero itself.
1 <= k <= 104






class Solution {
    public List<Integer> addToArrayForm(int[] num, int k) {
             
        final LinkedList<Integer> result = new LinkedList<>();
        int len = num.length - 1;
        
        while(len >= 0 || k != 0){
            
            if(len >= 0){
                k += num[len--];
            }
            
            result.addFirst(k % 10);
            k /= 10;
        }
            
        return result;
    }
}